AMB issues
 

We have been having some issues with our decoder lately. This summer we upgraded to the latest decoder. Over the summer during off-road we had some issues of cars not counting consistently. The loop was brand new from AMB. A car would go by one lap with a good signal. Next lap it was poor. It would effect some cars but not others. We couldn't nail down a cause for this. Later the same day it would pick cars up 10-15 feet away.

Now we are into onroad and we are having issues again. Sometimes it will pick you up as you enter the sweeper (10+ feet away from the loop). Other times it will pick you up as you cross the line. So you can not rely on the individual lap times.

What could be the cause of this or a solution?

Also what is an alternative to the AMB loop? I know Seattle RC Racers are using some kind of flat wire that's is not even noticeable as you drive over it.

There was a similar issue at a local track. It was the loop/cabling itself.

Assuming the transponders not counting are real MyLaps transponders, not MRT's..........

I would suggest testing the loop first. Disconnect the loop wire from the pigtail at the pickup and check the ohm's of the loop, should be 470 ohm's. Then check the coaxial for any breaks and the center wire is sticking out to about the end of the connector. Check the settings on the decoder, depending on your software the default settings usually work. There is a squelch feature that can be set to your tracks needs, higher the number the less sensitive to "ghost" transponders. Check the connections to the computer.

Some carpet tracks use a ribbon or flat wire equivalent to 18ga wire to avoid a bump! Don't bury the loop to deep!

What is the "Noise Level" when it is working well versus when it is playing up ?

How many hits do you get each time a transponder registers ?

As mentioned above measure the resistance of the loop before the loop amplifier. The loop amplifier must be close to the loop end. From the loop amplifier you will have your coaxial cable going back to the decoder. Ensure it does not run back to the decoder next to AC lines or VGA monitor cables etc. AMB recommend this run not be longer than 20 meters.

With a dodgey loop, transponders mounted on LiPo's or mounted vertically may have degraded hit counts and signal strength compared to other transponders.

I'm going to follow this thread.... I have 3 vehicles, all with REAL MyLaps transponders and only one of them will intermittently be counted at only one track that I go to. So strange. Some race days it works perfect, others days it will only count about half the laps. I've moved the transponder all over the place, no difference. I'm not the only one that is affected. Each week it's someone different.

I had an issue where I had the transponder (real mylaps RC4 hybrid) mounting vertically in the car which caused random issues and non-counting (low hit rate). Once mounting flat on the chassis or on top of the steering servo the problems went away. I never had this type of issue with older AMB transponders just the later generation small ones (RC3/RC4).

It might be worth doing a test to see if an older decoder does the same thing in the same place with the same loop set up, that could help find the cause. I have heard of cars not counting consistently and transponders picking up intermittently on the new decoders. It's not always easy to find the reason for laps being missed or having low hits, as Bob suggests, test the loop first as it's the place where there may be potential 'decoder issues' involving the loop and/or connectors etc.

Regarding transponders not counting, 'pure' RC4's are not backwards compatible with older decoders (don't work at all) and older MRT's need upgrading to the 'NS' new system spec to work ok (the new type flash twice when powered up, old type don't flash). Details/help about trade in's/PTX (NS) upgrades and offers
HERE: http://bitly.com/mrt-help or send me an email: [email protected]

Terry, My transponder is/was mounted flat on the chassis (RC10B44.3) with nothing around it. When the system wouldn't count laps, I had an older transponder that I would velcro to the top of the other transponder and the older one would work fine. The new transponder light blinks constantly and the older one doesn't blink at all, the light is on all the time.

Should I just use the older transponder at this particular track?

I've seen similar issues with the new RC4 transponders, right out of the pack they wouldn't work with our upgraded decoder. I've made it a point to buy the Hybrid transponders as I've never seen a hybrid have an issue counting laps.

Background Noise
 

Sounds like most things have been hit on but what is your background noise? That's the first thing I look at. The norm is around 22 - 26... 50 - 60 is pushing it... 80 & up cars start missing all the time. Used to be with the rc decoder this was a tell tail sign there was something wrong with the loop or loop cabling. .. But from what I understand this can be adjusted on the rc3 - rc4 decoders. Has anyone messed with the settings? Only thing I see missed is checking the COAX. .. it should read 100k ohms at either the BNC connector or the transformer end with the loop disconnected.

http://www.rctech.net/forum/attachme...mb-coax-iv.jpg

Our on-road track is a temporary track that we set up each race weekend, so it isn't setup right now to test anything on. It's indoors on a concrete floor. The loop gets taped down to the concrete under the carpet. I'll be setting it up this Friday, so I can try and check a few things. I'll try to update this thread then with what I find. The loop is brand new from AMB. Most everyone at our track uses the RC4 hybrid. I don't know of anyone using the RC4 (3-wire).

Ed - background noise is displayed on the decoder when it gets a hit from a transponder correct?

Thanks everyone for the suggestions and things to check. I'll report back Friday what I find.

I bet you have some electrical cabling under the concrete floor around the loop area. I have seen this issue on outdoor onroad tracks. They setup a track, and the electrical for parking lot lights, a sign that is out front of the property, or the electrical coming into the building is near the loop and cabling.

We make our own loop, and only have issues when the solder joint breaks, or when people dont lay the transponders flat in the chassis. MyLaps original documentation (RC2) says do not put the transponder on the servo...

Background noise is displayed all the time... its to the right of the loop on the display.. it might be in your software too. Transponder signal strength should be 60 points higher. Loops are easy to make.. I have a small 3' loop/bridge at the house so I can try/test things out. ;)

Edit:
Picture from another thread ... shows BN & TP signal strength. .. If there is a problem its the first thing I look for... then figure out why.

http://www.rctech.net/forum/attachme...x-test-iii.jpg

Interesting, you were doing what I suggested with the decoder problem Odin544 described, to run an older and new together to prove it's the new one not working for some unknown reason. As you're saying, I would use the older transponder at that particular track, and if possible have a spare hybrid or older type transponder just in case.

This is my test loop, about 12"x12". Uses a 3' bnc cable.

http://i252.photobucket.com/albums/h...ps46565fb4.jpg

loop noise issues
 

We have been having transponder issues as well at our track. it works fine for the longest time but all of a sudden it was having pickup issues.

Noise was high @ about 130, so we changed to rg6Q coax and dropped to 108. so what I did next was to isolate the decoder from anything electrical. I moved the box and loop to a spot that was at least 8' from any electrical outlets and now only down to 95 on the noise, I also have new loop wire from AMB. we worked on it all day and nothing got any better. off road indoor clay/sand track loop usually buried

what we tried is:

wire on ground with 470ohm resistor in far end of wire = 110 noise
no resistor on wire = inconsistent hits
wire on ground with resistor in connector box = best at around 95 noise
even tried a bridge and that didn't work at all.

JUST curious to what's in the black box at the end of your coax cable. I need one for my timing system and don't have the $200 for a new one

That black box is an older version of what you have now molded into the yellow COAX. That's the way they came on the older systems ... well at least the AMB20. Its filled with epoxy... nothing to see. I haven't seen anyone other then bigfix that makes them... and his are more then the MyLaps ones. I think you are stuck with having to buy a new one.

Hi Ed and rcaddict13, we make loop boxes they cost a lot less than $200. Send me a PM if you are interested, btw it's Terry at MRT :) (Model Racing Technology over in the UK).

Terry_S